GREENCREEK, Idaho (CNN) -- It was just 2˝ years ago when Elaine Sonnen found out that her 16-year-old son, Richard, had been planning a Columbine-style attack at his high school.

Richard Sonnen spent 16 months in mental health institutions after plotting to kill his high school classmates.

It would be a fitting payback to his high school classmates who Richard said relentlessly bullied him.

"I always wanted to get back at them," Richard Sonnen said of his classmates. "I always wanted to strangle them. ... I was always mad. I was always angry and I would come home and cry to mom and dad."

Both Richard and Elaine Sonnen spoke to CNN at the 45-acre family farm.

Unlike Columbine and recent school shootings at Northern Illinois University and Virginia Tech, Elaine Sonnen did see the warning signs in her son and was able to stop him.

Elaine and her husband, Tom, adopted Richard from a Bulgarian orphanage when he was just 4˝ years old.

"I mean, we just loved him, and he was just a big sparkle of life," she said.

But only a few months after they brought him home, they began to see another side of their son. He was angry and unpredictable.

Elaine Sonnen says that at age 6, Richard told her he wanted to kill her. She said he would shake with anger to the point that he'd scream at her, telling her he wanted to destroy her.

"People thought he was just the greatest kid in the world. Very polite, well-mannered, caring," Elaine Sonnen remembered. "At home, he could be anywhere from just a really helpful kid to a monster. A terrifying monster." Mother says son had 'two' personalities »

In junior high, he said, "evil" classmates started picking on him. Boys and girls, he said,bullied him until he couldn't take it anymore.

"I always wanted to get revenge," he said.

By the eighth grade, Richard was put on anti-psychotic medications. He had been diagnosed as bipolar and was suffering from obsessive compulsive disorder and other disorders.

In 1999, when the Columbine shootings happened, the Sonnens feared that Richard might do the same thing one day.

"We stopped and looked at each other and said, 'This could be Richard; some day this could be him,' " Elaine Sonnen said.

Years later, during his junior year in high school, they were right.

Fed up with the bullies, Richard says, he felt like an outcast and started looking for a way to get even.Secretly, he began reading books about Columbine in his school library. The shooters, Eric Harris and Dylan Klebold, became his heroes.

He even created a hit list of the classmates he planned to kill at Prairie High School in Cottonwood, Idaho.

"My plan was to set around bombs around the school. ... I analyzed a lot of where everybody sat and where everybody did their thing," he said. "I had pinpoints of where I wanted to go, where I wanted to do it."

Harvard Medical School psychologist William Pollack, who consulted on a 2002 federal government study of school shootings, said it found that most school shooters often had feelings of anger, sadness and isolation as well as homicidal and suicidal thoughts.

"We see a young man who obviously is telling us how depressed he was, how angry he was and how much he looked up to people who we know are very disturbed and very dangerous, and how close he came to killing people," said Pollack, who watched CNN's interview with Richard.

Elaine Sonnen found out about her son's plan during a conversation with him. She ordered him to write down the names of the eight students he wanted dead and then gave the list to his caseworker the next day. Later, he added a teacher and his mother and sister to the hit list.

She took immediate action and had her son committed to an Idaho mental institution. Over the next 16 months, he received treatment at several mental health facilities throughout Idaho.

"There, I opened up. I felt better. I moved on with myself," Richard said.

"They felt at that point ... they had done everything they could do for him," Elaine Sonnen added. "He was doing great. He could make it on his own. They had no question."

In January 2007, after almost a year and a half in mental institutions, Richard Sonnen started a new life at Lewis-Clark State College in Lewiston, Idaho. He was taking a cocktail of three anti-psychotic drugs to help him function.

"[For] the first time in 12 years, I was able to hold my son," said Elaine Sonnen. "So I knew he was on the road to be well."

Don't Miss

Everything seemed to be looking up, but in April 2007, three days after the Virginia Tech massacre, Richard's mother received a call from police. They told her Richard had made about four threats to carry out shootings at Lewis Clark State College and Lewiston High School.

Police told her Richard planned to go home, get some guns and go back to school to pull off a sniper attack from a clock tower on the college's campus, she said.

Police took him into protective custody and searched his apartment for clues. But, in the end, he was released because, authorities say, they didn't have enough evidence to charge him with a crime.

Richard said the whole incident was a big misunderstanding. He said he was telling people about his high school plot and never threatened his college or local high school.

But his mother doesn't believe his version of the story.

"No. I believe he made those threats," she said. "I still believe it."

Richard, now 19, signed an order banning him from campus for one year. Today, he lives on his own in Washington state. He's still on medication but not seeing a psychiatrist. Since he's over the age of 18, his mom can't force him to go.

Is Elaine Sonnen still afraid of her son?

"Yeah, at times, I'm very afraid," she said. "Because he still has a lot of anger towards me."

She said the signs are still there, and she fears what could happen if he ever stops taking his medicine.

"He's not getting the help and the insight from a professional that could see the signs," she said. "Because as a person with a mental illness, you have skewed thinking."

Even though Richard calls her the "greatest person in the world," Elaine Sonnen protects the family by keeping an alarm on her son's bedroom door when he comes home to visit.

So why are Richard Sonnen and his mother, Elaine, speaking out now? In the wake of the Northern Illinois University and Virginia Tech shootings, Richard wants young people experiencing the same symptoms he had to seek out help. His mother wants parents and authorities to listen for warning signs and to act fast and decisively.E-mail to a friend